Virtual clusters

Virtual clusters

You create a virtual cluster by configuring multiple virtual IP addresses (where each IP address typically corresponds to different Web sites or applications hosted on the cluster) on a single network adapter and then configuring different port rules for each virtual IP address. In this way, on each host you are able to have IP address-specific:

Port Range

Protocols

Affinity

Load weight

Filtering mode

By using a load weight of zero for specific virtual IP addresses, you can also define a virtual cluster that limits applications, Web sites, or virtual IP addresses to a specific subset of hosts within your Network Load Balancing (NLB) cluster. See the diagram below for an example of this use of virtual clusters.

This diagram depicts a four host Network Load Balancing cluster. Through the use of virtual clusters defined by IP address-specific load weights, Network Load Balancing directs network traffic as follows:

Users accessing Web Site A (IP address nnn.nnn.nnn.1) are directed to any of the four hosts

Users accessing Web site B (IP address nnn.nnn.nnn.2), which is a virtual cluster, are directed to hosts 1 and 2

Users accessing Web site C (IP address nnn.nnn.nnn.3), which is a virtual cluster, are directed to hosts 3 and 4

This is accomplished by setting the load weights as follows:

Load weight = 0 on hosts 3 and 4 for IP address xxx.xxx.xxx.2

Load weight = 0 on hosts 1 and 2 for IP address xxx.xxx.xxx.3.

Be aware that to use virtual clusters, all hosts in the cluster must be running one of the Windows Server 2003 family of products.